Pre‐morbid sleep disturbance and its association with stroke severity: results from the international INTERSTROKE study

Abstract Background and purpose Whilst sleep disturbances are associated with stroke, their association with stroke severity is less certain. In the INTERSTROKE study, the association of pre‐morbid sleep disturbance with stroke severity and functional outcome following stroke was evaluated. Methods INTERSTROKE is an international case–control study of first acute stroke. This analysis included cases who completed a standardized questionnaire concerning nine symptoms of sleep disturbance (sleep onset latency, duration, quality, nocturnal awakening, napping duration, whether a nap was planned, snoring, snorting and breathing cessation) in the month prior to stroke ( n = 2361). Two indices were derived representing sleep disturbance (range 0–9) and obstructive sleep apnoea (range 0–3) symptoms. Logistic regression was used to estimate the magnitude of association between symptoms and stroke severity defined by the modified Rankin Score. Results The mean age of participants was 62.9 years, and 42% were female. On multivariable analysis, there was a graded association between increasing number of sleep disturbance symptoms and initially severe stroke (2–3, odds ratio OR 1.44, 95% confidence interval CI 1.07–1.94; 4–5, OR 1.66, 95% CI 1.23–2.25; >5, OR 2.58, 95% CI 1.83–3.66). Having >5 sleep disturbance symptoms was associated with significantly increased odds of functional deterioration at 1 month (OR 1.54, 95% CI 1.01–2.34). A higher obstructive sleep apnoea score was also associated with significantly increased odds of initially severe stroke (2–3, OR 1.48; 95% CI 1.20–1.83) but not functional deterioration at 1 month (OR 1.19, 95% CI 0.93–1.52). Conclusions Sleep disturbance symptoms were common and associated with an increased odds of severe stroke and functional deterioration. Interventions to modify sleep disturbance may help prevent disabling stroke/improve functional outcomes and should be the subject of future research.